1. Field of the Invention
The invention disclosed herein is the improved utilization of catalytic materials suitable for use as the flameless heat source for powering an external-combustion engine or for transferring heat to any working fluid.
2. Description of the Prior Art
In many types of heat transfer devices a combustible fuel is employed and its heat of combustion is transferred to a working fluid. A common type in widespread current use employs an open plasma flame as the transfer medium. Another type employs a flameless combustion process by utilizing catalytic coatings at the surface area where heat is to be applied. Our invention relates to the latter type of heat transfer devices which may be exemplified by the U.S. Pat. Nos. 3,223,081 (E. B. Hunt) and 3,955,556 (J. B. Pangborn et al). In both patents, a catalytic material is used with a combustible fuel to provide for its combustion thereat and the catalytic material is in contact with a metallic surface which separates it from the working fluid which is to be heated. Two screens support the material having a catalyst thereon in the Hunt invention so that it contacts a metal case 4 which case in turn has the heat transfer liquid 8 on its other side. The Pangborn reference discloses the catalytic material in the form of a substrate liner or sleeve less than 1 mil thick (see column 5, lines 1-44). This thin sleeve contacts the metal chamber walls which walls are in direct contact with the fluid to be heated. This three layer system would thus have the catalytic material next to the metal wall which is, in turn, next to the working fluid to be heated.
What the prior art fails to disclose, and we disclose in our preferred embodiment, is the use of a catalytic material which is bonded directly on the surface whose opposite side has the working fluid into which the heat is to be transferred. We thereby eliminate the supporting substrate for the catalytic material. By directly applying the catalytic material and selecting a surface area of the desired size and shape, we have been able to very effectively transfer heat from the engine head of an external combustion engine to its working fluid. This has resulted in a very fuel efficient engine that is low in emission pollutants. Other heat transfer uses, such as heating water in a water heater, are also contemplated.